In Situ Functionalization of Carbon Nanotubes With Porphyrin‐Based Covalent Organic Frameworks as Electrode Material for Aqueous Supercapacitor

2D covalent organic frameworks (COFs) with redox‐active properties and an extended π‐conjugated architecture are excellent candidates for energy storage. In this work, we synthesized redox‐active, porphyrin‐based covalent organic frameworks (MT‐COF) by forming amide bonds between 5,10,15‐Tris(4‐aminophenyl)‐20‐phenylporphyrin (TPPTri‐NH 2 ) and 5,10,15‐Tris(4‐carboxyphenyl)‐20‐phenylporphyrin (TPPTri‐COOH). To enhance electrochemical performance, we designed in situ MT‐COF wrapping onto carbon nanotubes (SWCNT‐NH 2 and MWCNT) via covalent and noncovalent interactions to form SWCNT‐MT‐COF and MWCNT@MT‐COF nanoconjugates, respectively. In a three‐electrode setup, MWCNT@MT‐COF achieved a potential window of up to 2.2 V, with an impressive specific capacitance of 320.1 F/g at a current density of 0.35 A/g in 0.5 M K 2 SO 4 . The symmetric supercapacitor cell constructed with MWCNT@MT‐COF demonstrated a notable specific capacitance of 45.7 F/g and an energy density of 30.7 Wh/kg, along with a high areal capacitance of 30.5 mF cm –2 in 0.5 M K 2 SO 4 . Furthermore, it retained 96.4% of its capacitance after 20,000 Galvanostatic charge–discharge (GCD) cycles at 5 A/g.